Cooling pipe

ABSTRACT

A coolant pipe may include a micro fin including a rib and a channel which are continuously disposed on an interior circumference of the coolant pipe thereby forming a spiral flow path while the coolant passes the coolant pipe. In particular, a protruding height of the rib is between 30 μm and 200 μm.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to and the benefit of Korean Patent Application No. 10-2019-0062274, filed on May 28, 2019, the entire contents of which are incorporated herein by reference.

FIELD

The present disclosure relates to a coolant pipe to reduce resistance of coolant and improve heat exchange performance.

BACKGROUND

The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.

Generally, a heat exchanger of a vehicle transfers heat from a high temperature fluid to a low temperature fluid through an insulating wall, and is used for a heater, a cooler, an evaporator, a condenser, and the like.

The heat exchanger reuses the heat energy or adjusts the temperature of an operation fluid to suit the application, and is usually applicable to an engine room.

Meanwhile, exhaust gas of vehicles contain a large amount of harmful materials such as carbon monoxide, nitrogen oxides, hydrocarbons and the like.

Particularly, the amount of harmful materials such as nitrogen oxides increases as the engine temperature of the vehicle becomes higher. As a method for reducing such harmful materials, there is an exhaust gas recirculation system (EGR system) for reducing the generation of harmful materials by decreasing the combustion temperature in cylinders while recirculating the exhaust gas to an intake system.

The EGR system is a kind of a heat exchanger, and includes an EGR cooler for cooling high temperature exhaust gas using coolant.

The EGR cooler serves as a kind of a heat exchanger for exchanging heat between the exhaust gas and the coolant to prevent an excessive temperature rise of the exhaust gas.

In the EGR cooler, a plurality of tubes is provided in a cooler housing in which coolant flow paths are formed, and an exhaust gas flow path is formed in the tubes.

The coolant is supplied to the cooler housing via a coolant pipe.

We have discovered that when the coolant passes through the coolant pipe, the fluidity is deteriorated due to the viscous behavior occurring on the inner peripheral contact surface of the coolant pipe.

In addition, we have also found that the frictional resistance between the coolant and the coolant pipe may drop the thermal efficiency of the EGR cooler.

The above information disclosed in this Background section is only for enhancement of understanding of the background of the present disclosure and therefore it may contain information that does not form the prior art that is already known to a person of ordinary skill in the art.

SUMMARY

The present disclosure provides a coolant pipe that coolant is spirally rotated therein, and sheer stress generated between the coolant pipe and the coolant can be reduced or minimized.

In one form of the present disclosure, a coolant pipe may include: a micro fin including a rib and a channel which are continuously disposed on an interior circumference of the coolant pipe thereby forming a spiral flow path while the coolant passes through the coolant pipe. In particular, a protruding height of the rib is between 30 μm and 200 μm.

The micro fin may form a helix angle with respect to a longitudinal direction of the coolant pipe.

The helix angle may from 35 degree to 45 degree with respect to the longitudinal direction of the coolant pipe.

The rib may have a triangular cross-sectional shape.

The rib may have an oval cross-sectional shape.

The rib may have a rectangle cross-sectional shape and rounded corners.

The rib may have a rectangle cross-sectional shape and right angle corners.

The rib and the channel may be made of stainless steel.

In another form of the present disclosure, an EGR (exhaust gas recirculation) cooler may include a coolant pipe and a cooler housing, wherein the cooler housing and the coolant pipe are attached by brazing and/or welding so that the coolant flows into or out of the cooler housing through the coolant pipe.

According to an exemplary form of the present disclosure, since micro fin is formed on an interior circumference of the coolant pipe in contact with the coolant, the coolant is spirally rotated in the circumferential direction inside the coolant pipe and sheer stress generated between the coolant pipe 30 and the coolant can be reduced or minimized.

Further, the effects which may be obtained or predicted by the exemplary form of the present disclosure will be directly or implicitly disclosed in the detailed description of the exemplary forms of the present disclosure. That is, various effects which are predicted by the exemplary forms of the present disclosure will be disclosed in the detailed description to be described below.

Further areas of applicability will become apparent from the description provided herein. It should be understood that the description and specific examples are intended for purposes of illustration only and are not intended to limit the scope of the present disclosure.

DRAWINGS

In order that the disclosure may be well understood, there will now be described various forms thereof, given by way of example, reference being made to the accompanying drawings, in which:

FIG. 1 is a schematic view of an EGR cooler to which a coolant pipe according to one form of the present disclosure is applied;

FIG. 2A is a view of a coolant pipe according to an exemplary form of the present disclosure;

FIG. 2B is an enlarged view of the coolant pipe in FIG. 2A;

FIG. 3 is a cross sectional view of a coolant pipe according to an exemplary form of the present disclosure.

FIGS. 4A, 4B, 4C and 4D are cross sectional views of a micro fin according to exemplary forms of the present disclosure; and

FIG. 5 is a view for explaining a coolant path in which coolant flows according to an exemplary form of the present disclosure.

The drawings described herein are for illustration purposes only and are not intended to limit the scope of the present disclosure in any way.

DETAILED DESCRIPTION

The following description is merely exemplary in nature and is not intended to limit the present disclosure, application, or uses. It should be understood that throughout the drawings, corresponding reference numerals indicate like or corresponding parts and features.

Herein, the present disclosure will be described more fully hereinafter with reference to the accompanying drawings, in which exemplary forms of the present disclosure are shown. As those skilled in the art would realize, the described forms may be modified in various different ways, all without departing from the spirit or scope of the present disclosure.

FIG. 1 is a schematic view of an EGR cooler to which a coolant pipe according to one form of the present disclosure is applied. FIG. 2A is a view of a coolant pipe according to an exemplary form of the present disclosure. FIG. 2B is an enlarged view of the coolant pipe in FIG. 2A. FIG. 3 is a cross sectional view of a coolant pipe according to an exemplary form of the present disclosure. FIGS. 4A, 4B, 4C and 4D are cross sectional views of a micro fin according to exemplary forms of the present disclosure. And FIG. 5 is a view for explaining a coolant path in which coolant flows according to an exemplary form of the present disclosure.

The structure of the coolant pipe according to one form of the present disclosure may be applied to the portion where the coolant moves in various heat exchangers of a vehicle.

For example, the heat exchanger applied to the vehicle may be a radiator, a heater core, a condenser and various coolers.

Referring to FIG. 1, a coolant pipe according to one form of the present disclosure is applied to an EGR cooler 1 in an EGR (Exhaust Gas Recirculation) system configured between an exhaust manifold and an intake manifold.

However, the coolant pipe according to the form of the present disclosure is not limited to being applied to the EGR cooler, but may be applied to various heat exchangers of the vehicle, as described above.

The EGR cooler 1 suppresses the generation of nitrogen oxide by recirculating a portion of the exhaust gas from an engine to an intake manifold to reduce the combust temperature in a cylinder.

The EGR cooler 1 includes a cooler housing 10 provided with a pair of cover 11 at both ends. A gas inflow pipe 13 connected with an exhaust manifold and a gas exhaust pipe 15 connected with an intake manifold are provided in the covers 11, respectively.

A plurality of tube 20 in which the exhaust gas flows is stacked in the cooler housing 10 with a predetermined interval.

The tube 20 is formed in a rectangular tube shape having open ends at both ends and is fixed through a cap 21. One end of the tube 20 is connected with the gas inflow pipe 13, and the other end of the tube 20 is connected with the gas exhaust pipe 15.

The exhaust gas flows into the tube 20 through the gas inflow pipe 13, and the exhaust gas is exhausted outside from the tube 20 through the gas exhaust pipe 15.

A coolant inlet 17 and a coolant outlet 19 which is connected with the coolant pipe 30 are formed in the cooler housing 10.

That is, the coolant flowing in the coolant pipe 30 flows into the inside of the cooler housing 10 through the coolant inlet, and the coolant which is heat-exchanged with the exhaust gas in the cooler housing 10 is discharged to the coolant pipe 30 through the coolant outlet 19.

Referring to FIGS. 2A and 2B, the coolant pipe 30 has a coolant path formed therein, and a micro fin 40 is integrally formed on an interior circumference in contact with the coolant.

The micro fin 40 includes a rib 41 and a channel 43 which is continuously disposed.

The rib 41 and the channel 43 may form a predetermined angle (A) with respect to a longitudinal direction L of the coolant flowing in the coolant pipe 30.

In one form, the rib 41 and the channel 43 may form a helix angle with respect to a longitudinal direction L of the coolant flowing in the coolant pipe 30 (refer to FIG. 3).

The predetermined angle A refers to an angle at which the rib 41 is inclined with respect to a straight line L formed in the longitudinal direction of the coolant pipe 30.

In one form, the predetermined angle A is formed to be inclined in a range of about 35 degree to 45 degree with respect to the straight line L formed in the longitudinal direction of the coolant pipe 30.

That is, as the predetermined angle A becomes smaller, the rib 41 becomes closer to the straight line L in the longitudinal direction of the coolant pipe 30.

The predetermined angle A may be determined based on 45 degrees that reduces or minimize sheer force between the coolant and the coolant pipe 40 by using an equation 1. And the predetermined angle A may be determined within a predetermined range based on 45 degrees in consideration of formability of the coolant pipe.

$\begin{matrix} {\sigma = {{\frac{P}{A} \cdot \cos^{2}}\mspace{14mu} \theta}} & \left( {{Equation}\mspace{14mu} 1} \right) \end{matrix}$

where, σ denotes sheer force, P denotes hydraulic pressure of the coolant, A denotes an area of the coolant pipe, and θ denotes helix angle.

When the helix angle is excessively greater than 45 degrees, a flow resistance of the coolant is increased, and when the helix angle is excessively smaller than 45 degrees, the helical flow of the coolant is not properly formed. Therefore, the helix angle may be determined at 45 degrees.

The micro fin 40 including the rib 41 and the channel 43 may be formed in various shapes as follows.

Referring to FIG. 4A, the rib 41 a of the micro fin may have a triangular cross-sectional shape.

The channel 43 a is formed between the adjacent ribs 41 a and ribs 41 a formed on the inner surface of the cooling pipe 30 in a spiral manner.

At this time, a protruding height HA of the rib 41 a having triangular cross-sectional shape may be between 30 μm and 200 μm.

Referring to FIG. 4B, rib 41 b of the micro fin may have an oval cross-sectional shape.

The channel 43 b is formed between the adjacent ribs 41 b and ribs 41 b formed on the inner surface of the cooling pipe 30 in a spiral manner.

In another form, a protruding height HB of the rib 41 b having an oval cross-sectional shape is between 30 μm and 200 μm.

Referring to FIG. 4C, the rib 41 c of the micro fin may have a rectangle cross-sectional shape and rounded corners.

The channel 43 c is formed between the adjacent ribs 41 c and ribs 41 c formed on the inner surface of the cooling pipe 30 in a spiral manner.

In other form, a protruding height HC of the rib 41 c having a rectangular cross-sectional shape is between 30 μm and 200 μm.

Referring to FIG. 4D, the rib 41 d of the micro fin may be formed in a rectangle cross-sectional shape, and corners of the ribs may be right angle.

The channel 43 d is formed between the adjacent ribs 41 d and ribs 41 d formed on the inner surface of the cooling pipe 30 in a spiral manner.

In one form, a protruding height HD of the rib 41 d having a rectangular cross-sectional shape is between 30 μm and 200 μm.

Since the maximum height of each of the ribs 41 a to 41 d is set in the range of 200 μm or less, it is possible to inhibit or prevent an anomalous phenomenon such as occurrence of precipitates in a joint portion between the coolant pipe 30 and other parts or cracking of the joint portion when the coolant pipe 30 is assembled with other parts through brazing.

Referring to FIG. 5, the micro fin 40 formed as described above is formed on an interior circumference of the coolant pipe 30, and the coolant passing through the coolant pipe 30 forms a spiral flow path.

In other words, the coolant flowing in the coolant pipe 30 forms a spiral flow path at the inner circumferential surface where the micro fins 40 and the coolant contact each other, and a straight flow path is formed at the center of the coolant pipe 30.

Since the spiral flow path of the coolant is formed on the interior circumference of the coolant pipe 30 by the micro pin 40, fluidity of the coolant and cooling performance can be improved by reducing the frictional force between the interior circumference of the coolant pipe 30 and the coolant.

Further, since the micro fin 40 is formed on the interior circumference of the coolant pipe 30 in contact with the coolant, the coolant is spirally rotated in the circumferential direction inside the coolant pipe 30 and sheer stress generated between the coolant pipe 30 and the coolant can be reduced or minimized.

In addition, by applying the micro fin 40 to the coolant pipe 30 according to the present disclosure, a turbulent flow of the coolant is generated at the inner surface of the cooling water pipe 30. Therefore, the surface friction between the cooling water and the coolant pipe 30 can be reduced and fluidity of the coolant can be improved.

While this present disclosure has been described in connection with what is presently considered to be practical exemplary forms, it is to be understood that the present disclosure is not limited to the disclosed forms. On the contrary, it is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the present disclosure.

DESCRIPTION OF SYMBOLS

1: EGR cooler

10: cooler housing

11: cover

13: gas inflow pipe

15: gas exhaust pipe

17: coolant inlet

19: coolant outlet

20: tube

21: cap

30: coolant pipe

40: micro fin

41: rib

43: channel 

What is claimed is:
 1. A coolant pipe for flowing coolant, comprising; a micro fin including a rib and a channel which are continuously disposed on an interior circumference of the coolant pipe, the micro fin configured to form a spiral flow path while the coolant passes through the coolant pipe, wherein a protruding height of the rib is between 30 μm and 200 μm.
 2. The coolant pipe of claim 1, wherein the micro fin forms a helix angle with respect to a longitudinal direction of the coolant pipe.
 3. The coolant pipe of claim 2, wherein the helix angle is from 35 degree to 45 degree with respect to the longitudinal direction of the coolant pipe.
 4. The coolant pipe of claim 1, wherein the rib has a triangular cross-sectional shape.
 5. The coolant pipe of claim 1, wherein the rib has an oval cross-sectional shape.
 6. The coolant pipe of claim 1, wherein the rib has a rectangle cross-sectional shape and rounded corners.
 7. The coolant pipe of claim 1, wherein the rib has a rectangle cross-sectional shape and right angle corners.
 8. The coolant pipe of claim 1, wherein the rib and the channel are made of stainless steel.
 9. An exhaust gas recirculation (EGR) cooler including the coolant pipe according to claim 1, and a cooler housing, wherein the cooler housing and the coolant pipe are attached by brazing and welding so that the coolant flows into or out of the cooler housing through the coolant pipe. 